A Virginia sweetspire is heavy with blooms. Submitted Photo

Butterfly bushes (Buddleja davidii) are a popular shrub used in home landscapes to attract butterflies and pollinators. Unfortunately, these beautiful shrubs can be invasive and harmful to local ecosystems.

Originally from China, the butterfly bush was introduced to the United States as an ornamental plant. Its prolific, colorful blooms caught gardeners’ attention, and the plant quickly gained popularity. Easy to grow and attractive to butterflies, it seemed to be an ideal choice for gardeners desiring to promote pollinator populations. But outside of the maintained garden, the plant spreads rapidly and out-competes native species.

Butterfly bush blooms produce tiny seeds that are picked up by the wind, landing on streams, riverbanks, pastures and other places where they can lie dormant until environmental conditions allow them to sprout. A single flower cluster can produce 40,000 seeds, and a large backyard shrub can create up to three million seeds. Initially, its aggressive nature wasn’t apparent because regular lawn mowing, weeding and mulching kept its seeds under control. While butterfly bushes produce an ample amount of nectar, they do not support the larval states of butterfly development.

The Pennsylvania Department of Conservation and Natural Resources lists the butterfly bush as an invasive species. Because of its prolific seeding potential, the sale of butterfly bushes is banned in some states. Plant breeders have developed less invasive cultivars of the butterfly bush. To be considered as non-invasive, germination must be significantly reduced. But even at 98% reduction of fertility, tens of thousands of fertile seeds are produced by individual shrubs.

For gardeners looking to replace their butterfly bushes or to add pollinator-friendly shrubs to their landscapes, these native plants are attractive alternatives and support more butterfly life stages. All of these native shrubs are hardy in Butler County.

Virginia sweetspire (Itea virginica) is a fragrant shrub that thrives in sun or partial shade and moist soil, growing to a height of 6 to 10 feet. It blooms with long white floral tassels in May and June, providing nectar food for bees and butterflies, while seeds in fall and winter will offer sustenance to songbirds. With crimson leaves in the fall this is a three-season beauty. This shrub is deer resistant.

New Jersey tea shrub is visited frequently by pollinators. Submitted Photo

Stephanie Brundage

New Jersey tea (Ceanothus americanus) is a versatile shrub that can be used for hedges or planted on rocky slopes. It prefers sun or partial shade and well-drained soil. As a larval host plant for butterflies like the summer azure (Celastrina neglecta), it supports butterfly populations while adding beauty to your garden. New Jersey tea shrubs grow to a height of 2 to 4 feet.

Steeple bush (Spiraea tomentosa), with its dense, finger-like blooms in pink and red, attracts native bees, birds and butterflies. In the fall, its leaves turn yellow in color. This sun-loving shrub grows to a height of 3 to 5 feet.

Common milkweed (Asclepias syriaca) is not a shrub; however, perennial milkweeds provide the perfect combination of nectar for the adult monarch butterfly (Danaus plexippus) and leaves for its larval form. Striking in height, milkweed also contains a sap that makes it deer resistant. Simply grown by seed, this is one perennial you can plant in the back of sunny flowerbeds and enjoy every year.

Choose native, pollinator-friendly shrubs in place of butterfly bushes to make a positive impact on your local environment. The butterfly bush may seem like a harmless addition to your garden, but its invasive nature poses a significant threat to native plants and wildlife beyond your garden border. By opting for native alternatives, you can create a garden that is both beautiful and beneficial to the environment.

Penn State Extension has additional information on butterfly bushes at extension.psu.edu/avoiding-invasives-butterfly-bush and other invasive plant species at extension.psu.edu/invasive-shrubs-to-avoid.

If you have questions about invasive plants or native, pollinator-friendly shrubs, call the Master Gardeners of Butler County Garden Hotline at 724-287 4761, ext. 7, or email the Master Gardeners at butlermg@psu.edu.

Danielle Fannin is a Penn State Extension Master Gardener of Butler County.

Danielle Fannin